Inherited retinal diseases (IRDs) are characterized by progressive vision loss. There are over 270 causative IRD genes, and variants within the same gene can cause clinically distinct disorders. One example is RLBP1, which encodes CRALBP. CRALBP is an essential protein in the rod and cone visual cycles that take place primarily in the retinal pigment epithelium (RPE) but also in Müller cells of the neuroretina. RLBP1 variants lead to three clinical subtypes: Bothnia dystrophy, retinitis punctata albescens, and Newfoundland rod-cone dystrophy. We modeled RLBP1-IRD subtypes using patient-specific induced pluripotent stem cell (iPSC)-derived RPE and identified pathophysiological markers that served as pertinent therapeutic read-outs. We developed an AAV2/5-mediated gene-supplementation strategy and performed a proof-of-concept study in the human models, which was validated in vivo in an Rlbp1−/− murine model. Most importantly, we identified a previously unsuspected smaller CRALBP isoform that is naturally and differentially expressed both in the human and murine retina. This previously unidentified isoform is produced from an alternative methionine initiation site. This work provides further insights into CRALBP expression and RLBP1-associated pathophysiology and raises important considerations for successful gene-supplementation therapy.

中文翻译：

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双 CRALBP 亚型揭晓：iPSC 衍生的视网膜建模和 AAV2/5-RLBP1 基因转移引发了对有效治疗的考虑


遗传性视网膜疾病 （IRD） 的特征是进行性视力丧失。有超过 270 个致病 IRD 基因，同一基因内的变异可导致临床上不同的疾病。一个例子是 RLBP1，它编码 CRALBP。CRALBP 是视杆细胞和视锥细胞视觉周期中的一种必需蛋白，主要发生在视网膜色素上皮 （RPE） 中，但也发生在神经视网膜的 Müller 细胞中。RLBP1 变异可导致 3 种临床亚型：波的尼亚型营养不良、点状白斑型视网膜炎和纽芬兰视杆锥细胞营养不良。我们使用患者特异性诱导多能干细胞 （iPSC） 衍生的 RPE 对 RLBP1-IRD 亚型进行建模，并确定了作为相关治疗读数的病理生理标志物。我们开发了一种 AAV2/5 介导的基因补充策略，并在人类模型中进行了概念验证研究，该研究在 Rlbp1 - / - 小鼠模型中进行了体内验证 。最重要的是，我们鉴定了一种以前未被怀疑的较小 CRALBP 亚型，它在人类和小鼠视网膜中均自然和差异表达。这种以前未鉴定的亚型是由替代的蛋氨酸起始位点产生的。这项工作进一步深入了解了 CRALBP 表达和 RLBP1 相关病理生理学，并为成功的基因补充治疗提出了重要的考虑因素。